1. Field of the Invention
The present invention relates to a triptycene derivative and an organic light emitting diode (OLED), and more particularly to a triptycene derivative having symmetric or asymmetric substituents and organic light emitting diode using the same.
2. Description of the Prior Art
OLED (organic light-emitting diode), also commonly known as organic electroluminescent device, is a kind of LED having a organic layer as the active layer. OLED has been spotlighted due to a lot of advantages, such as self illumination, wider visual angle (>170°), shorter response time (˜μs), higher contrast, higher efficiency, lower power consumption, higher brightness, lower operative voltage (3-10V), thinner size (<2 mm), flexibility and so on. In recent years, OLED has been gradually used in flat panel display. In comparison to LCD monitor, OLED displays are provided with OLED pixel array having self-luminous characteristics and therefore do not require additional back light module. To apply OLED into a full-color display, it is necessary and important to develop red, green, and blue light emitting materials with appropriate chromaticity and high light-emitting efficiency.
Excitons generated from recombining holes and electrons have triplet state or singlet state for its spin state. Singlet exciton relaxation radiates fluorescence and triplet exciton relaxation radiates phosphorescence. Phosphorescence achieves 3-fold efficiency comparing to fluorescence and may greatly enhance the IQE (internal quantum efficiency) of devices up to 100% by adopting metal complexes in electroluminescent configuration to achieve strong spin-orbital coupling and mixing of singlets and triplets. Therefore, phosphorescent metal complexes are now adopted as phosphorescent dopants in the emitting layer of OLED.
In addition, by using a doping method in the emitting layer, self-quenching of the emitting materials can be reduced greatly to enhance the efficiency of the device. Therefore, the search for proper host materials becomes noteworthy since host materials must be capable of capturing carriers and have good energy transfer properties, high glass transition temperature, high thermal stability and appropriate energy gap of the singlet and triplet excited states. However, it would be difficult to search for host materials that fully meet the criteria and there is still some room for host material development in OLED.
Regarding triptycene derivatives, Taiwan patent No. 1390007 disclosed triptycene derivatives having tri-substituents as listed below.

US patent application No. 20110272680 disclosed triptycene derivatives as listed below.

To sum up, to develop novel host materials is now a current goal.